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Tree Implementation in C++

A tree is a common hierarchical data structure in computer science used to express hierarchical relationships or organizations. Each node can have a parent and zero or more children, and they are all connected by edges. Considering their adaptability and wide range of uses, trees may be used to represent file systems, organize data in databases, and create data structures like binary search trees.

A tree may be created in C++ by applying classes and pointers. Each tree node should have its class, which should include information and pointers to the nodes that make up its children. This is the fundamental concept. This is the basic idea. The node connections serve as a representation of the tree's hierarchical relationships. There are so many different types of trees, including binary trees, AVL trees, and others, each having unique properties and uses.

The implementation includes setting up procedures for growing and contracting the tree, as well as for executing operations on the tree structure. Trees are a crucial component of algorithm design and data organization, providing effective answers to a range of computational issues.

Let's Implement the Binary Tree

A binary tree is implemented in C++ by developing a data structure that indicates the hierarchical relationship that exists between nodes. Only two children, known as the left child and the right child, can exist for each node in a binary tree. In computer science, binary trees are frequently utilized and have many uses, such as in search algorithms, data organization, and expression interpretation.

The TreeNode class and the BinaryTree class are normally the two primary components that are defined in order to create a binary tree in C++.

1. TreeNode Class: A single node within a binary tree is represented by the TreeNode class. It has characteristics like:

  1. Data: The node's related value.
  2. Left Child Pointer: A pointer to the node's left child, or nullptr if there isn't one.
  3. Right Child Pointer: A pointer to the right child node, or nullptr if there isn't one.

2. BinaryTree Class: The BinaryTree class is responsible for containing the whole binary tree structure. It provides techniques for modifying the tree, such as adding nodes, moving across the tree, and looking for certain values. Important methods and concepts include:

  1. Insertion (Adding Nodes): The insertion operation is essential in the construction of a binary tree. It means growing the tree while maintaining its hierarchy by adding a new node. The new node's value is compared to the old nodes, beginning with the root node. If the value is lower, the left subtree is examined; if the value is higher, the right subtree is reviewed. Recursively, this procedure continues until an acceptable location for insertion is discovered. The ordered nodes of the binary tree must be maintained, which depends on this process.
  2. Traversal (Visiting Nodes): We can traverse the binary tree's nodes to visit and interact with them. There are three main traversal techniques:
  3. Inorder Traversal: This approach traverses the left subtree, then the current node, and lastly, the right subtree. In a binary search tree, it is used to generate nodes in ascending order.
  4. Preorder traversal: In this case, the left and right subtrees of the current node are explored first. It is used to copy trees and print phrases using the prefix notation.
  5. Postorder Traversal: This traversal travels to the left and right subtrees before the current node. It is frequently employed for expression evaluation or memory deallocation.
  6. Searching: Searching includes locating a certain value within the binary tree. Comparisons between the target value and node values take place starting at the root. The left subtree is looked into if the goal is smaller; the right subtree is searched if the target is larger. Recursively, this procedure goes on until the goal is located or a leaf node, which denotes absence, is reached.
  7. Deletion: Deletion is the removal of a node from the binary tree. There are nodes with no children, one child, and two children among the cases. A node with two children can frequently be deleted, and then its in-order successor is used in its place. By doing this, the hierarchical structure can be maintained without compromising the order of the tree.

Finding Minimum and Maximum:

These methods identify the binary tree's minimum and maximum values, respectively. The greatest value can be discovered by moving through the rightmost nodes, whereas the minimum value can be found by moving through the leftmost nodes. Useful for locating tree extremities.

Calculating Height and Checking Balance:

To calculate height, find the binary tree's greatest depth by following its length from root to leaf node. By ensuring that the heights of the left and right subtrees vary by no more than one, checking for balance guarantees that operations go smoothly.

Counting nodes and calculating the diameter:

Counting nodes, including internal and leaf nodes, helps in determining the size of the binary tree. Finding the longest path between any two nodes involves calculating the diameter. This makes it easier to understand the properties and structure of the tree and enables operators to make smart decisions.


Example to implement the binary tree:


Tree Implementation in C++


This C++ code provides an example of creating a binary tree and releasing its elements using an in-order traverse. This code's goal is to construct a straightforward binary tree structure and demonstrate how in-order traversal works to output nodes' values in ascending order.

A node in the binary tree is represented by the TreeNode structure. Each node has an integer value as well as left and right child pointers that are initially initialized to NULL for each node. The constructor sets the node's children pointers to NULL and initializes it with the provided value.

The in-order traversal of the binary tree and printing of the node values are done by the recursive printBinaryTree function. It traverses the left subtree first, then prints the value of the present node, followed by traversing the right subtree.

The root node of the binary tree is first created with a value of 1 in the main function's initial line of code. After that, the root's left and right child nodes are constructed with the values 2 and 3, respectively. A left child node with the value 4 is also created for the root's left child. Thus, the binary tree structure is formed.

Finally, the root node will be provided as an argument while executing the printBinaryTree method. The output will display the values of the nodes in ascending order, separated by spaces, as a result of in-order traversal. The result in the current case will be 4 2 1 3, which is compatible with the values of the nodes that were visited throughout the in-order traverse.

Applications of Binary Tree in C++

  • Data Storage and Retrieval: When storing data in a way that makes efficient searching, insertion, and deletion operations possible, binary search trees are frequently utilized. They continue to maintain the property that every element in a node's right subtree is greater than that node, and every element in its left subtree is less than that node. Fast searching and retrieval of items is made possible by this characteristic.
  • Sorting Algorithms: Balanced binary search trees like AVL trees and Red-Black trees, as well as heapsort, depend heavily on binary trees. These trees enable maintaining an element's sorted order, enabling effective sorting and preserving the order as new elements are added or deleted.
  • Huffman Coding: Based on character frequency, Huffman Coding provides characters with variable-length codes. This approach is employed in data compression. For determining the best prefix codes for effective data compression, Huffman trees are utilized.
  • Graph Representation: In many applications, hierarchical relationships are represented by binary trees, which are particular types of graphs. They can, for example, display family trees, hierarchical menus, and organizational hierarchies in user interfaces.
  • Expression Evaluation: To represent mathematical expressions in a way that enables their evaluation, binary expression trees are utilized. The operands are represented by the children of each node in the tree; each represents an operator.
  • AI and Game Development: For decision-making processes, binary trees are employed in AI algorithms and game creation. In games and simulations, AI decision routes are frequently represented using decision trees and behavior trees.
  • Networking and Routing: In order to effectively find paths in networks, routing and networking algorithms employ binary trees. They aid in streamlining the procedure for determining the quickest or most effective path between nodes.

Types of Binary Tree in C++

The acronym for BST is Binary Search Tree, which is a hierarchical data structure. The Binary Search Tree contains a maximum of two children for each node. The node that is left is less than the value of the parent, and the right one is greater than the parent node.

BSTs are advantageous for maintaining and organizing ordered data because of this characteristic, which facilitates effective search, insertion, and deletion operations. Fast data retrieval and manipulation are made possible by the balanced structure of the tree, which guarantees that these operations have logarithmic time complexity.

  1. Balanced Binary Trees: These are binary trees that are designed to preserve their balance in order to provide optimal performance throughout several operations. AVL trees and Red-Black trees are two examples of balanced binary trees. The left and right subtrees of each node must have a height difference between them of no more than one AVL tree. During insertions and deletions, Red-Black trees utilize a set of balancing criteria to make sure the tree remains approximately balanced.
  2. Binary Expression Trees: These trees are used to represent mathematical expressions in such a way that their evaluation is conceivable. The operands are each node's children, which each represent an operator. Mathematical expressions are evaluated and processed using binary expression trees.
  3. Full Binary Trees: A full binary tree only contains two or zero children at each node. This kind of tree is frequently used in applications, such as some tree-based algorithms and tree-based data structures, when actions need traversing every level of the tree.
  4. Complete binary trees: Complete binary trees are similar to the balanced trees with all levels, possibly with the exception of the final one, filled. Complete binary trees are frequently utilized in binary heaps and array-based binary tree representations.
  5. Perfect Binary Trees: A perfect binary tree is a full binary tree in which each leaf node is at the same level, resulting in a balanced structure. Some indexing strategies and data storage techniques are based on perfect binary trees.


In conclusion, the C++ implementation of trees offers a flexible and powerful data structure that finds use in a number of programming and computer science fields. Trees provide data with a hierarchical structure, making it easier to store, manipulate, and retrieve data. The choice of tree type depends on the particular requirements of the current situation and might range from straightforward binary trees to more complex structures like balanced trees and heaps.

The creation of nodes and the definition of their relationships, frequently accompanied by traversal and manipulation algorithms, represent the implementation of trees. While balanced trees provide consistent performance across operations, binary search trees offer effective searching capabilities. Priority queues and sorting algorithms depend heavily on heaps, whereas specialized trees like expression trees handle mathematical analyses.

To effectively optimize algorithms and address a variety of issues, it is crucial to comprehend the principles of tree structures, their operations, and their temporal complexities. Because of their adaptability, trees are an essential tool in computer science that helps programmers solve problems with data organization, optimization, and information retrieval. Programmers may develop beautiful solutions to challenging issues by using their understanding of tree implementation, whether it is in databases, compilers, algorithms, or other applications. The Binary trees play a major role in all aspects.

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